asp.net mvc 4 - Operation is not valid due to the current state of the object in MVC4 in StoredProcedure -

i getting error [system.invalidoperationexception] = {"operation not valid due current state of object."}

i getting list of values contining datatype oracleclob executing storedprocedure

here code

try         {             string connectionstrings = configurationmanager.connectionstrings["oracleconnection"].connectionstring;             oracleconnection con = new oracleconnection(connectionstrings);             con.open();             oraclecommand command = new oraclecommand();             command.commandtype = system.data.commandtype.storedprocedure;             command.commandtext = "pkg_rtmi_web.prc_get_rtmi_signature";             command.parameters.add("p_masag", oracledbtype.varchar2).direction =                 system.data.parameterdirection.input;             command.parameters["p_masag"].value = masagr_id;              command.parameters.add("p_sig", oracledbtype.refcursor).direction = system.data.parameterdirection.output;              oracledatareader dr = command.executereader();             con.close();             oracleclob clob = null;             while(dr.read())             {                 clob = dr.getoracleclob(0);             }             return clob;          } catch (exception ex)         {             /// exception block             baseobject.issuccessful = false;             baseobject.message = "[rtmisignature]: " + ex.message;              return null;         } 

got error in line oracledatareader dr = command.executereader();

also added line web.config

<appsettings> <add key="aspnet:maxhttpcollectionkeys" value="15000" /> </appsettings> 

but same results note: clob contains more 12k characters